1. Field of the Invention
The invention relates to a hydraulic fluid replenishment device. More particularly, it relates to such a device for use with a hydraulic system embodied in a portable tool, under works or factory-floor conditions.
2. Background of the Related Art
By a replenishment device is meant a device which will allow the addition of new hydraulic fluid to a system to replace fluid lost e.g. by leakage. Such loss leaves air in the system, and it is necessary to remove this air. Preferably this air is removed by pressurizing the hydraulic system to force the air out. In practice, some old hydraulic fluid, which may be mixed with air bubbles, may also be forced out of the system, in order to ensure that all the air has been removed.
It is common to replenish the hydraulic fluid in a hydraulic system by means of a hydraulic pump. However, such apparatus is large, heavy, expensive and complicated to use. When the hydraulic system to be replenished is embodied in a hand-held tool, for example a hand-held blind-rivet installation gun, there is a need for a replenishment device which is small, lightweight, inexpensive and easy to use. The device should also provide for the removal of air, and any old hydraulic fluid mixed with it, from the system before feeding new hydraulic fluid to it, and should not allow old hydraulic fluid to contaminate the new fluid.